This invention relates to an imaging apparatus for Factory Automation (FA) suitable for carrying out imaging operation of, e.g., object moving at high speed, and a control device therefor.
The applicant of this application has proposed, in the Japanese Patent Application Laid Open No. 119776/1992, an imaging apparatus having electronic shutter function, which is adapted for controlling charge storage time of a solid-state image pick-up device (CCD image sensor) of the IT (Interline Transfer) type to thereby carry out exposure time adjustment without use of mechanical iris. In this imaging apparatus, the shutter speed can be changed in dependency upon movement of object by using the electronic shutter function. This imaging apparatus is advantageous particularly in taking thereinto picture image in high speed moving body.
In such an imaging apparatus, e.g., used mainly for FA and adapted for carrying out image pick-up operation of moving object, e.g., a configuration as shown in FIG. 1 is employed. When an object 201 moving on a movement path 200 has moved to the front portion of an image pick-up section 202, a position detecting section 203 detects this to deliver, to a shutter signal generating circuit 204, a trigger signal which falls to low level at time t11 of FIG. 2(a).
The shutter signal generating circuit 204 is operative so that when the trigger signal is delivered thereto, it delivers, to a CCD control circuit 205, a shutter signal which rises at time t11 of FIG. 2(b). The CCD control circuit 205 is operative so that when the shutter signal is delivered thereto, it stops supply of a shutter control signal for sweeping out electric charges (hereinafter simply referred to as charges) stored at the photo-electric converting section of the CCD image sensor 206 into the overflow drain. Thus, effective charges begin to be stored into respective pixels of the photo-electric converting section of the CCD image sensor 206.
The CCD control circuit 205 is supplied with a vertical synchronizing signal which falls at time t11 and rises at time t12 of FIG. 2(c) and a horizontal synchronizing signal shown in FIG. 2(d) from a synchronizing signal generating circuit 207. The CCD control circuit 205 is operative so that when the shutter control signal is delivered thereto, it carries out nine (9) count operations of pulses (i.e. counts nine (9) pulses) of the horizontal synchronizing signal shown in FIG. 2(d) from the time t11 at which the vertical synchronizing signal shown in FIG. 2(c) falls thereafter to carry out several hundred count operations of clock pulses thereafter to deliver a read-out signal to the CCD image sensor 206 at time t13 shown in FIG. 2(e).
Thus, for a time period from the time when the shutter control signal is delivered to the CCD image sensor 206 at time t11 of FIG. 2(b) until the read-out signal is delivered to the CCD image sensor 206 at time t13 of FIG. 2(e), charges corresponding to image pick-up light irradiated through an imaging (image pick-up) lens 208 are stored in the CCD image sensor 206. The time period from the time t11 to the time t13 is charge storage time.
In this case, FIG. 2(f) indicates vertical blanking period VBLK.
The charges which have been read out from the CCD image sensor 206 are delivered to a signal processing circuit 209 as an image pick-up signal. The signal processing circuit 209 implements, to the image pick-up signal, a signal processing to add synchronizing signal, etc. to output it as a video signal through an output terminal 210. The video signal outputted through the output terminal 210 is delivered to, e.g., monitor. Thus, it is possible to analyze the state of the object 201 in the case where the object 201 is caused to be moved.
Since such an imaging apparatus for carrying out image pick-up operation of moving object is mainly used for FA, there are instances where the object 201 shown in FIG. 1 is caused to be moved at high speed and imaging is desired to be carried out by high speed shutter, e.g., 1/10000 sec. etc.
However, in the above-mentioned imaging apparatus, nine count operations of pulses of the horizontal synchronizing signal are carried out from, e.g., falling of the vertical synchronizing signal thereafter to deliver a read-out signal to the CCD image sensor at the timing when several hundreds of clock pulses have been counted. Namely, the output timing of the read-out signal is fixedly set in advance on the basis of the pixel arrangement of the CCD image sensor.
Accordingly, the charge storage time of the imaging apparatus could not be shortened down to a value required from the falling time of the vertical synchronizing signal to the time when the read-out signal is outputted. For this reason, the conventional imaging apparatus did not carry out image pick-up operation by high speed shutter such as 1/1000 sec., etc.
The imaging apparatus starts storage of effective charges in dependency upon trigger signal delivered from the position detecting section 203 as described above. Namely, the imaging apparatus becomes operative in dependency upon the timing of the trigger signal delivered from the position detecting section 203. When a trigger signal is delivered at an arbitrary timing as shown in FIG. 3(a), for example, the imaging apparatus delivers a read-out signal shown in FIG. 3(b) to the CCD image sensor after a predetermined charge storage time, i.e., exposure time to read out the charges stored in respective pixels of the photoelectric converting section to the vertical transfer section and to generate, at the same time, a vertical synchronizing signal V-SYNC to output the charges which have been read out to the vertical transfer section as an image pick-up signal through a horizontal transfer section in the state synchronized with the vertical synchronizing signal V-SYNC thus generated.
Moreover, the applicant of this application has proposed, in the Japanese Patent Application Laid Open No. 1525502/1994, an imaging system adapted to generate a modulated synchronizing signal on the basis of a trigger signal generated at an arbitrary timing, thereby making it possible to carry out image pick-up operation by high speed shutter such as 1/1000 sec., etc in the state synchronized with the synchronizing signal of random period.
Meanwhile, in the conventional imaging system as described above, image pick-up operation by high speed shutter can be carried out, but the exposure time period cannot be adjustably set in succession over a broad range.
Thus, an object of this invention is to provide an imaging apparatus which is capable of carrying out image pick-up operation in synchronism with synchronizing signal of random period, and which permits continuous adjustable control of the exposure time period over a broad range, and a control device therefor.
An imaging apparatus according to this invention comprises: a solid-state image pick-up device including light receiving means adapted for producing charges corresponding to quantity of light incident thereto, vertical transfer means to which charges produced at the light receiving means are transferred, horizontal transfer means for outputting the charges transferred through the vertical transfer means, and a charge sweep-out section for sweeping out the charges stored at the light receiving means in accordance with a shutter control signal; trigger signal generating means for generating a trigger signal; pulse width adjustable setting means for generating, on the basis of input timing of the trigger signal, a trigger pulse signal of which pulse width can be adjustably set; signal generating means for outputting a shutter control signal in which the leading edge of the trigger pulse signal is caused to be timing of reference and a synchronizing signal in which the trailing edge of the trigger pulse signal is caused to be timing of reference; drive signal generating means for outputting, on the basis of timing of the synchronizing signal, a read-out signal for transferring the charges stored at the light receiving means to the vertical transfer means and a transfer signal for outputting, through the horizontal transfer means, the charges which have been read out to the vertical transfer means; and drive means for driving the solid-state image pick-up device on the basis of the shutter control signal, the read-out signal and the transfer signal, thus to carry out image pick-up operation of object for an effective exposure time period corresponding to pulse width of the trigger pulse signal.
Moreover, an imaging apparatus according to this invention comprises: a solid-state image pick-up device including light receiving means adapted for producing charges corresponding to quantity of light incident thereto, vertical transfer means to which the charges produced at the light receiving means are transferred, horizontal transfer means for outputting the charges transferred through the vertical transfer means, and charge sweep-out means for sweeping out the charges stored at the light receiving means in accordance with a control signal; trigger signal generating means for outputting a trigger signal; pulse width adjustable setting means for generating, on the basis of input timing of the trigger signal, a trigger pulse signal of which pulse width can be adjustably set; signal generating means for outputting a first shutter control signal generated on the basis of timing of the trailing edge of the trigger pulse signal, a second shutter control signal generated on the basis of timing of the leading edge of the trigger pulse signal and a synchronizing signal generated on the basis of timing of the trailing edge of the trigger pulse signal; signal selector means for selectively outputting one of the first shutter control signal and the second shutter control signal; drive signal generating means for generating, on the basis of the synchronizing signal, a read-out signal for transferring the charges stored at the light receiving means to the vertical transfer means and a transfer signal for outputting, through the horizontal transfer means, the charges which have been read out to the vertical transfer means; and drive means for driving the solid-state image pick-up device on the basis of the first shutter control signal or the second shutter control signal selected by the signal selector means, the read-out signal and the transfer signal.
A control device for an imaging apparatus according to this invention includes: detector means for detecting an object to output a detection signal; pulse width adjustable setting means for outputting, on the basis of the detection signal, a trigger pulse signal of which pulse width can be adjustably set; and signal generating means for generating a shutter control signal in which the leading edge of the trigger pulse signal is caused to be timing of reference and a synchronizing signal in which the trailing edge of the trigger pulse signal is caused to be timing of reference to deliver the synchronizing signal and the shutter control signal to the imaging apparatus to allow it to carry out image pick-up operation for exposure time period corresponding to pulse width of the trigger pulse signal.
In addition, a control device for an imaging apparatus according to this invention comprises: detector means for detecting an object to output a detection signal; pulse width adjustable setting means for generating, on the basis of the detection signal, a trigger pulse signal of which pulse width can be adjustably set; signal generating means for outputting a first shutter control signal generated on the basis of timing of the trailing edge of the trigger pulse signal, a second shutter control signal generated on the basis of timing of the leading edge of the trigger pulse signal and a synchronizing signal generated on the basis of timing of the trailing edge of the trigger pulse signal; and signal selector means for selectively outputting one of the first shutter control signal and the second shutter control signal to deliver, to the imaging apparatus, the synchronizing signal and the first shutter control signal or the second shutter control signal.